Dear petsc-users, I am trying with a student to modify the MG example 65 to use mat-shells instead of assembled matrices. Our use case is for a method that will use custom shell operators and shell interpolation/restrictions. To start we have modified ex65 and tried to replace the standard restriction/interpolation with a shell matrix that performs the same operations on the DMDA grids. I attach our modifications to ex65. The problem is that the code sometimes completes execution and sometimes errors out like $ ./ex65shell -ksp_monitor -pc_type mg -da_refine 2 -ksp_rtol 1e-1
Created DMshell 0x55bbc83c91a0 (0x55bbc8390a80) Calling KSPSolve from main computeRHS on grid 513 computeMatrix on grid 513 Inside Coarsen Created DMshell 0x55bbc84c5270 (0x55bbc84b2ff0) Inside Coarsen Created DMshell 0x55bbc84e0a30 (0x55bbc84bdb60) Create interpolation from 0x55bbc84c5270(0x55bbc84b2ff0) to 0x55bbc83c91a0(0x55bbc8390a80) [0]PETSC ERROR: --------------------- Error Message
[0]PETSC ERROR: Invalid pointer [0]PETSC ERROR: Invalid Pointer to PetscObject: Argument 'obj' (parameter # 1) [0]PETSC ERROR: See https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!Y... for trouble shooting. [0]PETSC ERROR: Petsc Release Version 3.22.0, unknown [0]PETSC ERROR: ./ex65shell with 1 MPI process(es) and PETSC_ARCH on signalkuppe by matteo Tue Dec 10 12:55:12 2024 [0]PETSC ERROR: Configure options: --prefix=/home/matteo/software/petscsaved/3.22-opt/ PETSC_DIR=/home/matteo/software/petsc --PETSC_ARCH=dbg --with-debugging=1 --with-st rict-petscerrorcode --download-hdf5 --download-ml --with-metis --with-parmetis --with-gmsh --with-triangle --with-zlib --with-p4est-dir=~/software/p4est/local/ [0]PETSC ERROR: #1 PetscObjectReference() at /home/matteo/software/petsc/src/sys/objects/inherit.c:620 [0]PETSC ERROR: #2 PCMGSetRScale() at /home/matteo/software/petsc/src/ksp/pc/impls/mg/mgfunc.c:394 [0]PETSC ERROR: #3 PCSetUp_MG() at /home/matteo/software/petsc/src/ksp/pc/impls/mg/mg.c:998 [0]PETSC ERROR: #4 PCSetUp() at /home/matteo/software/petsc/src/ksp/pc/interface/precon.c:1071 [0]PETSC ERROR: #5 KSPSetUp() at /home/matteo/software/petsc/src/ksp/ksp/interface/itfunc.c:415 [0]PETSC ERROR: #6 KSPSolve_Private() at /home/matteo/software/petsc/src/ksp/ksp/interface/itfunc.c:826 [0]PETSC ERROR: #7 KSPSolve() at /home/matteo/software/petsc/src/ksp/ksp/interface/itfunc.c:1075 [0]PETSC ERROR: #8 main() at ../src/ex65shell.c:79 [0]PETSC ERROR: PETSc Option Table entries: [0]PETSC ERROR: -da_refine 2 (source: command line) [0]PETSC ERROR: -ksp_monitor (source: command line) [0]PETSC ERROR: -ksp_rtol 1e-1 (source: command line) [0]PETSC ERROR: -pc_type mg (source: command line) [0]PETSC ERROR: ----------------End of Error Message -------send entire error message to [email protected] In all cases valgrind complains like $ valgrind ./ex65shell -ksp_monitor -pc_type mg -da_refine 2 -ksp_rtol 1e-1 -int_view ascii::ascii_info ==2130767== Memcheck, a memory error detector ==2130767== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al. ==2130767== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info ==2130767== Command: ./ex65shell -ksp_monitor -pc_type mg -da_refine 2 -ksp_rtol 1e-1 -int_view ascii::ascii_info ==2130767== hwloc x86 backend cannot work under Valgrind, disabling. May be reenabled by dumping CPUIDs with hwloc-gather-cpuid and reloading them under Valgrind with HWLOC_CPUID_PATH.
Created DMshell 0xfbf50f0 (0xfb49480) Calling KSPSolve from main computeRHS on grid 513 computeMatrix on grid 513 Inside Coarsen Created DMshell 0xff404a0 (0xff062d0) Inside Coarsen Created DMshell 0xff78ca0 (0xff4a530) Create interpolation from 0xff404a0(0xff062d0) to 0xfbf50f0(0xfb49480) Mat Object: 1 MPI process type: shell rows=513, cols=257 ==2130767== Conditional jump or move depends on uninitialised value(s) ==2130767== at 0x83FDAAE: PCSetUp_MG (mg.c:998) ==2130767== by 0x8620C04: PCSetUp (precon.c:1071) ==2130767== by 0x7DA78D5: KSPSetUp (itfunc.c:415) ==2130767== by 0x7DB2093: KSPSolve_Private (itfunc.c:826) ==2130767== by 0x7DB7A53: KSPSolve (itfunc.c:1075) ==2130767== by 0x10D2F7: main (ex65shell.c:79) ==2130767== ==2130767== Conditional jump or move depends on uninitialised value(s) ==2130767== at 0x5794061: VecDestroy (vector.c:570) ==2130767== by 0x83FDC36: PCSetUp_MG (mg.c:999) ==2130767== by 0x8620C04: PCSetUp (precon.c:1071) ==2130767== by 0x7DA78D5: KSPSetUp (itfunc.c:415) ==2130767== by 0x7DB2093: KSPSolve_Private (itfunc.c:826) ==2130767== by 0x7DB7A53: KSPSolve (itfunc.c:1075) ==2130767== by 0x10D2F7: main (ex65shell.c:79) ==2130767==
We are clearly doing something wrong since PCSetUp_MG (mg.c:998) is an area of code where I wouldn't expect we would enter. Can you advise on the proper way to achieve our goal? Best regards Matteo